Bad SCSI performance with 2.6.14 and Fusion-MPT

Hi,

I'm seeing really bad scsi performance with 2.6.14 in combination with Fusion MPT and amd64. The same behavior was seen in 2.6.14-git13.

The controller in question identifies itself as "LSI Logic / Symbios Logic 53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI (rev 07)", PCI ID 1000:0030.

Starting with 2.6.14 (didn't test the releases between 2.6.13 and 2.6.14) the resync rate of the software raid dropped to about 2mb/sec on a raid1 array over two scsi disks (normally I get around 60-80mb/sec), doing a dd from one disk to the other supported those values. I can't give exact measures since a "sync" call hangs since half an hour (was a bit too much data for testing) but vmstat shows:

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----

 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 0  5      0 23873224 8198000  24288    0    0   463   259   71    23  0  0 83 17
 0  5      0 23872968 8198000  24288    0    0     0  4096  273    48  0  0 75 25
 0  5      0 23873340 8198000  24288    0    0     0     0  271    50  0  0 75 25
 0  4      0 23873084 8198000  24288    0    0     0  4096  270    49  0  0 75 24
 0  4      0 23873120 8198000  24288    0    0     0  4096  274    54  0  0 75 25
 0  4      0 23873120 8198000  24288    0    0     0     0  270    44  0  0 75 25
 0  4      0 23873136 8198000  24288    0    0     0  4096  272    51  0  0 75 25

which is bad.

Any ideas?

best regards,
Michael Renner